I have a strange entry on my Skymiles account. Back in July, after the first batch of miles posted, I also had an entry coded:

SkyMiles MC CheckCard 2x Spend on Delta Bonus

I've received this three out of the five months that I've had the account opened, and it always posts the same day as the regular miles from the check card.

The first month was 67 miles, the third month was 15 miles, and the last time it was 11 miles.

I'm not at all concerned about such a small amount of miles, but the coding would lead me to believe that there is some sort of 2x bonus that I don't know about.

I have NOT purchsed anything from Delta, or Delta.com, so it can't be some sort of airline bonus.